Field of the Disclosure
The invention relates to a phenolic modified polyesters for use in can coatings. The invention particularly relates to a coating systems that come in contact with food and beverages.
Background of the Disclosure
In the food and beverage industry of both today and the past, the preservation of food has been an issue that has tested the limits of the technology of the times. For example, margarine was the product of a Chemist seeking to win a prize for making a butter substitute for use by the French armed forces in the middle of the 19th century. Early efforts of preserving foods were sometimes tragic. The Franklin Expedition, a 19th century effort to find a Northwest passage, was doomed, at least in part, by its provisions. This early effort of “canning” used lead to seal the seams of the cans which contaminated the food therein.
Fortunately modern efforts of canning are safe and becoming safer. Metal containers for receiving foods and beverages generally have one or more coatings to prevent contact between the filled product and metal. This is to prevent or minimize corrosion to the metal by the product and any disadvantageous influences on the quality of the product. For producing containers of this type, such as cans of tin-plated or chromium-plated steels or aluminium, metal sheets are used which, prior to their shaping (such as for three-piece can production) or deformation (such as for deep drawing process), are coated with suitable coating compositions.
In producing cans for foods and beverages, coatings are required which are extremely flexible and have a low order of toxicity. Furthermore, filled food cans are often sterilized. Sterilization processes may expose food containers, such as cans, to temperatures of 135° C. or greater. It follows then, that coatings used to preserve food must therefore be sufficiently stable at those temperatures and must be capable of adhering to the surface of the metal.
Recently, the use of coatings formulated with Bisphenol A have come under scrutiny. It would be desirable in the art of coating food containers to use a coating produced using little or no Bisphenol A.